A fiber channel fabric typically uses a set of interconnected host bus adapters ((HBAs) which connects a host in/out bus to a computer terminal's memory), bridges, storage devices and switches. A storage area network (SAN) installation may include multiple fabrics for redundancy. Typically, a fabric may be considered as a set of switches sharing inter-switch links (ISLs) together with the devices to which they are connected. A SAN with multiple switches not connected by ISLs provide multiple fabrics.
Existing fiber channel fabrics have scalability limitations with the continued increase in the support of ports and virtual SANs (VSANs) on each switch. Indeed, when the principal link on a switch fails, there is a flood to fabric (Build-fabric) reconfiguration phase on all ports, all VSANs and all switches in the fabric. In turn, this leads to increase in the system load and may potentially result in control frame drops, instability, or large re-convergence times for the fabric on each VSAN.
More particularly, in a fibre-channel fabric, when a switch starts a build fabric (BF) phase, it will flood the network with BF frames by sending a BF_REQ frame through each interface and, for each interface, the switch will wait for a corresponding BF_RESP response frame. In a similar manner, when a switch starts a reconfigure fabric (RCF) phase, it will flood the network with RCF frames by sending a reconfigure request frame (RCF_REQ frame) through each connected interface, and also, for each interface, it will wait for a corresponding reconfigure response frame (RCF_RESP frame).